1. Field of the Invention
The present invention relates to a weak-magnetic field sensor using printed circuit board manufacturing technique and a method of manufacturing the same, and more particularly to a weak-magnetic field sensor using printed circuit board manufacturing technique and a method of manufacturing the same which is adapted to be mounted on a mobile communication terminal to detect the Earth""s magnetic field to obtain positional information.
2. Description of the Prior Art
In the recent trend of offering various additional information services in the spread of mobile phones and mobile terminals, a positional information service becomes established as an essential service, and more accurate and convenient services are required hereafter.
To achieve positional information, it is necessary to provide a sensor capable of precisely determining a current position. As such means for providing positional information, a weak-magnetic field sensor which is intended to detect the Earth""s magnetic field to obtain positional information has been used. As a component commonly used in such a weak-magnetic field sensor, there is a flux gate sensor.
The flux gate sensor uses highly permeable magnetic strips for its core components. The flux gate sensor is comprised of a primary coil wound around one of the two magnetic cores and a secondary coil wound around the other of the magnetic cores, and is capable of recognizing a current position by detecting a difference between voltage generated from the primary coil and voltage generated from the secondary coil due to variations of magnetic fields of the cores.
Such a conventional flux gate sensor is manufactured in such a way that two cylindrical cores made of highly permeable magnetic material are wound with copper wires in a certain direction. More specifically, a copper wire as a driving coil (a primary coil) is wound around a magnetic core in a certain direction while maintaining constant spacing and pressure. Subsequently, a pickup coil (a secondary coil) is wound around the magnetic core to detect a magnetic field generated from the magnetic core due to the driving coil. As is the case with the winding of the driving coil, a copper wire as the pickup coil is wound at a constant spacing under constant pressure.
As such, such a flux gate, which is fabricated by winding copper wires, is comprised of a driving coil and a pickup coil for detecting a magnetic field generated from the driving coil. The copper coils are wound around the magnetic cores utilizing a wire coil technology well known in the art. At this point, the secondary coil must be wound to be directed in an X axis direction and an Y axis direction so as to obtain positional information of magnetic field. However, although a conventional flux gate sensor must maintain positional accuracy of a wound coil, it is difficult to maintain the positional accuracy. Since the positional accuracy is easily affected by temperature, light or surface material due to such configuration, accuracy of its attributes is deteriorated.
In addition, since the flux gate sensor is fabricated such that a coil is directly wound around a magnetic core, it has a disadvantage in that the coil is frequently cut. Moreover, since the sensor itself becomes large, it is not compatible with the trend toward miniaturization and weight reduction of electric appliances. The enlargement of the sensor requires increased electricity consumption, so that the sensor cannot achieve miniaturization and reduction of electricity consumption of electric appliances.
To overcome disadvantages of such a conventional flux gate sensor, a weak-magnetic field sensor is proposed in U.S. Pat. Nos. 5,936,403 and 6,270,686, which is manufactured in such a way that amorphous boards having circular etched portions are stacked on both upper and lower surfaces of a glass epoxy base having specific conductive patterns to form an amorphous flat board core, and glass epoxy bases etched to form X coils and Y coils are stacked on the amorphous flat board core. However, since the flux gate sensor disclosed in U.S. Pat. Nos. 5,936,403 and 6,270,686 require a process comprising preparing the amorphous flat board core by etching the amorphous boards to have circular etched portions and stacking of amorphous boards while conforming to the circular etched portions, and stacking epoxy base boards having an X coil and an Y coil etched thereon on the amorphous core, its manufacturing process is complicated and high manufacturing cost is incurred due to stacking of many amorphous boards.
The present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a weak-magnetic field sensor using printed circuit board manufacturing technique and a method of manufacturing the same which can detect weak-magnetic fields with precision and provide accurate positional information.
Another object of the present invention is to provide a weak-magnetic field sensor using printed circuit board manufacturing technique and a method of manufacturing the same which is capable of meeting the need for high density mounting required in a field of application such as mobile phones by accomplishing miniaturization, excellent magnetic efficiency and low electric power consumption by an etching technique for a printed circuit board.
A further object of the present invention is to provide a weak-magnetic field sensor using printed circuit board manufacturing technique which is simply constructed, easily manufactured, and reduced in manufacturing cost by simple circuit construction and a method of manufacturing the same.
In order to accomplish the above object, the present invention provides a weak-magnetic field sensor using printed circuit board manufacturing technique comprising: a first base boardxe2x80x94a CCL(Copper Clad Laminate) which is formed at its upper and lower surfaces with first driving patterns such that the upper and lower first driving patterns are electrically connected to each other; a first stacked boardxe2x80x94prepregs and worked copper foils which are stacked on upper and lower surfaces of the first base board and which are formed with magnetic layers to be parallel to each other and patterned in a certain shape; and a second stacked boardxe2x80x94prepregs and copper foils which are stacked on outer surfaces of the first stacked boards and which are formed with second driving patterns electrically connected to the first driving patterns of the first base board to surround magnetic layers and formed with pickup patterns to surround the first and second driving patterns.
Furthermore, the present invention provides a method of manufacturing a weak-magnetic field sensor using printed circuit board manufacturing technique, comprising the steps of: providing first driving patterns on upper and lower surfaces of a first base board by forming first via-holes at the first base board to connect the upper and lower driving patterns to each other followed by plating of the via-holes, exposing and etching; preparing the first stacked board by stacking and pressing prepregs, worked copper foils and magnetic bodies(amorphous metal)on both sides of the first base board followed by exposing, developing and etching; preparing the second stacked boards by stacking and pressing prepregs and copper foils on both sides of the first stacked board; forming second via-holes at the first and second stacked boards, and forming through holes at the first base board and the first and second stacked boards; and providing second driving patterns on the second stacked boards to be electrically connected to the first driving patterns by the second via-holes and to surround the magnetic cores, and providing pickup patterns on the upper and lower second stacked boards to be electrically connected to each other by the through holes and to surround the first driving patterns by plating, exposing, developing and etching the second stacked board.